CVE-2026-100662

HIGHPre-NVD 7.57.5—
EchelonGraph scoreHIGH confidence

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-26. A secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type 0x02). The handler accepts an attacker-declared string-literal length of up to Integer.MAX_VALUE (~2 GiB) for the Name Length and Value Length fields of the "Insert With Literal Name" instruction (RFC 9204 §4.3.3), with no per-instruction or per-literal length cap and no cumulation-size limit; the existing HTTP/3 limits (maxHeaderListSize, maxUnknownFramePayloadLength, DEFAULT_MAX_FIELD_SECTION_SIZE) are not applied to this handler. A remote, unauthenticated peer with an established HTTP/3 connection to a default Netty HTTP/3 server can declare a very large literal length and then trickle fewer bytes than declared, causing the ByteToMessageDecoder MERGE cumulator to retain and grow the per-connection buffer, and ultimately triggering a large byte-array allocation. This leads to unbounded per-connection heap growth and OutOfMemoryError, resulting in denial of service. Fixed in 4.2.18.Final.

CVSS v3
7.5
EG Score
7.5HIGHhigh confidence
EG Risk
38
EG Risk 38/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.3%
EPSS %ILE
25th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 26, 2026

Last Modified

September 30, 2026

Advisory Details (2)

Auto-updated Sep 26, 2026
🔬 Proof of concept available. Patch available. Sources: github.
generic

Netty HTTP/3 QPACK encoder-stream unbounded memory exhaustion DoS | Advisories | VulnCheck

https://www.vulncheck.com/advisories/netty-http-3-qpack-encoder-stream-unbounded-memory-exhaustion-dos
github Patch Available🟡 PoC Available

Netty HTTP/3 QPACK encoder-stream Insert-With-Literal-Name unbounded length causes memory-exhaustion DoS · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-f64r-x647-cg8w

Vendor Advisories for CVE-2026-100662(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 30× in last 7d / 41× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-10-05 09:40 UTCEG score recompute
  2. 2026-10-05 09:40 UTCGHSA enrichment
  3. 2026-10-04 23:21 UTCEPSS rescore
  4. 2026-10-04 22:16 UTCGHSA enrichment
  5. 2026-10-04 10:52 UTCGHSA enrichment
  6. 2026-10-03 23:29 UTCEG score recompute
  7. 2026-10-03 23:29 UTCGHSA enrichment
  8. 2026-10-03 14:25 UTCEPSS rescore
  9. 2026-10-03 12:03 UTCGHSA enrichment
  10. 2026-10-03 00:39 UTCEG score recompute
  11. 2026-10-03 00:39 UTCGHSA enrichment
  12. 2026-10-02 13:15 UTCGHSA enrichment
  13. 2026-10-02 01:52 UTCEG score recompute
  14. 2026-10-02 01:52 UTCGHSA enrichment
  15. 2026-10-01 19:49 UTCEPSS rescore
  16. 2026-10-01 14:27 UTCGHSA enrichment
  17. 2026-10-01 03:03 UTCGHSA enrichment
  18. 2026-09-30 15:39 UTCEG score recompute
  19. 2026-09-30 15:39 UTCGHSA enrichment
  20. 2026-09-30 15:02 UTCEPSS rescore
  21. 2026-09-30 13:04 UTCGHSA enrichment
  22. 2026-09-30 01:38 UTCEG score recompute
  23. 2026-09-30 01:38 UTCGHSA enrichment
  24. 2026-09-29 15:20 UTCEPSS rescore
  25. 2026-09-29 14:14 UTCGHSA enrichment
Show 16 more
  1. 2026-09-29 02:51 UTCEG score recompute
  2. 2026-09-29 02:51 UTCGHSA enrichment
  3. 2026-09-28 15:27 UTCEG score recompute
  4. 2026-09-28 15:27 UTCGHSA enrichment
  5. 2026-09-28 13:50 UTCEPSS rescore
  6. 2026-09-28 04:48 UTCGHSA enrichment
  7. 2026-09-27 17:24 UTCEG score recompute
  8. 2026-09-27 17:24 UTCGHSA enrichment
  9. 2026-09-27 16:36 UTCEG score recompute
  10. 2026-09-27 16:35 UTCGHSA enrichment
  11. 2026-09-27 13:21 UTCGHSA enrichment
  12. 2026-09-27 01:57 UTCEG score recompute
  13. 2026-09-27 01:57 UTCGHSA enrichment
  14. 2026-09-26 14:33 UTCEG score recompute
  15. 2026-09-26 13:37 UTCEG score recompute
  16. 2026-09-26 13:30 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-100662?
CVE-2026-100662 is a high vulnerability published on September 26, 2026. Netty's HTTP/3 codec (io.netty:netty-codec-http3) versions 4.2.0.Final through 4.2.17.Final contain an uncontrolled resource consumption vulnerability in the QPACK encoder-stream instruction decoder (QpackEncoderHandler, installed on the peer-initiated unidirectional QPACK encoder stream, type…
When was CVE-2026-100662 disclosed?
CVE-2026-100662 was first published on September 26, 2026, with the most recent update on September 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-100662 actively exploited?
CVE-2026-100662 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-100662?
CVE-2026-100662 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-100662?
A fix for CVE-2026-100662 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-100662 are linked in the Vendor Advisories panel on this page.

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